TEIN Street Basis Z, Street Advance Z, Flex Z, Mono Sport and RX1 Compared

This article was written by Coilovers.com Owner and Principal, Lou Tortola.

TEIN Flex Z vs Street Advance Z comes down to mounts, ride height method and service. Both use a twin-tube damper with 16-level damping. The Flex Z adds full-length height adjustment and, on most fitments, a mount designed for your model.

That is the short answer. The longer one covers five TEIN coilover kits we list: Street Basis Z, Street Advance Z, Flex Z, Mono Sport and RX1. TEIN was founded in Yokohama in 1985. Inside, they are built for different drivers. Here is how they line up, spec by spec, using TEIN's own published details.

The TEIN Lineup at a Glance

TEIN groups its street kits by damper type, damping adjustment and how you set ride height. Every kit on this list lets you adjust ride height. Only one has fixed damping.

TEIN describes its twin-tube design as giving a longer stroke with a smaller repulsive force than a regular monotube. TEIN links that to ride comfort. If you want the full engineering story, our guide to monotube vs twin tube dampers covers it.

TEIN Flex Z vs Street Advance Z: Where They Differ

These two are the most cross-shopped kits in the TEIN range. On paper, the damping is the same: 16 levels, one knob, compression and rebound moving together. So what changes?

Upper mounts

TEIN says the Street Advance Z and Street Basis Z use the car's original upper mounts, and those mounts are not in the kit. You reuse what you have. If your factory mounts are tired, plan to replace them during the install.

The Flex Z includes a mount designed for each model. TEIN shows both reinforced rubber and pillow ball mounts in the range, and its front strut pillow ball mounts allow camber adjustment. Which mount comes with your kit depends on the car. On some models without mount plates, the original mounts are used. Check the product page for your fitment.

How ride height is set

The Flex Z uses full-length adjustment. TEIN says adjusting ride height this way has little effect on ride quality. You change the body length, so preload and the damper's bump travel stay where they were.

On the Street Advance Z, TEIN describes adjusting ride height by moving the lower spring seat up or down. That works, and it keeps the kit simple. Just know that the spring perch is doing the height work, so check your travel after a big drop.

Service

TEIN describes the Street Advance Z as sealed, with the unit closed by crimping the metal. For the Flex Z, TEIN says it provides a replacement service rather than an overhaul, and revalving is available. Neither is meant to be rebuilt at home. If you want a kit you can have overhauled, look at Mono Sport.

Street Basis Z: Fixed Damping, Adjustable Height

The Street Basis Z is TEIN's set-and-forget kit. Damping is fixed at the factory. You set ride height once and drive. It uses your original upper mounts, like the Street Advance Z.

That suits a daily driver who wants a lower stance and firmer control without fiddling with knobs. You cannot add EDFC later, because the damper has no adjuster. If you think you will want to tune damping down the road, start one step up. Our guide to adjustable coilovers walks through that choice.

On the 2015 to 2021 WRX STI (VAF), we list the TEIN Street Basis Z for the VAF. Flex Z, RX1 and Mono Sport kits are listed for it too. That one chassis shows most of the range side by side.

RX1: Ride Comfort With a Hydraulic Bump Stop

RX1 is TEIN's comfort-first twin-tube kit. TEIN's own page puts ride comfort for every seat at the front of the pitch. It also mentions setup options for sport driving.

The feature that sets it apart is the Hydraulic Bump Stopper. Near full compression, it narrows the base valve ports, and a relief valve limits sudden force spikes. TEIN says it converts the impact to heat and absorbs it. You still run the normal bump rubbers with it.

RX1 also has 16-level damping that adjusts compression and rebound together, full-length height adjustment and optional EDFC. TEIN provides a replacement service on it rather than an overhaul. We list the TEIN RX1 for the 2015 to 2021 WRX STI. RX1 fitments also cover the Civic Type R FK8 and FL5, the BRZ and the 86.

Mono Sport: TEIN's Monotube Option

Mono Sport is the one monotube kit in this group. TEIN fully separates the oil and gas chambers and says this prevents aeration. Damping is 16-level and linear, with compression and rebound adjusting together. TEIN says its ADVANCE M.S.V. sub-valve widens the adjustable range about threefold.

Ride height is full-length. Mounts are included and designed for each model, in reinforced rubber or pillow ball. Front strut pillow ball mounts allow camber adjustment, and some models use the OE mounts.

TEIN pitches Mono Sport for circuits, winding roads and everyday street driving. Settings are tuned per car. It is the kit here that TEIN will overhaul, and revalving is available. On the 2015 to 2021 STI, we list the TEIN Mono Sport for the WRX STI.

EDFC5: In-Cabin Damping Control

EDFC is TEIN's electronic damping force controller. It is a TEIN-only add-on, not a coilover kit. Small motors replace the damping knobs, and you adjust from the driver's seat.

The current version is EDFC5, TEIN's fifth generation. It needs both a Controller Kit and an EDFC Motor Kit, and it has a 96-level mode. TEIN announced it in December 2022 for release in January 2023. Compatibility depends on both the car and the damper.

TEIN lists Street Advance Z, Flex Z, Mono Sport and RX1 as EDFC compatible. Street Basis Z is not. Some cars are excluded even when the kit is compatible. Confirm the part numbers on the listing, or call us before you buy the controller.

Which TEIN Kit Fits How You Drive

Here is how we situate the lineup for the drivers who call us.

Spring rate is set per car on every one of these kits. Check it on the product page. None of these coilover kits is a way to cut unsprung weight, either. That mass is mostly wheel, tire, hub and brakes, so lighter wheels do more there than any damper swap.

For the bigger picture on the brand, read our TEIN coilovers overview. If you are weighing TEIN against other value-focused kits, our piece on value coilovers covers Solo-Werks too.

How TEIN Sits Among the Brands We Carry

TEIN brings Japanese engineering with the Flex Z 16-stage damping option and EDFC electronic damping force controller as an in-cabin add-on. It adds deep Japanese-platform fitment depth across Honda, Toyota, Nissan, and Subaru chassis.

Other brands we carry serve other drivers. BC Racing lists the BR, DS, ER, RM, HM and ZR Series, and ZX appears as an option on some listings. Custom rates and Swift Springs upgrades are available on most fitments. KW brings German engineering with TÜV certification on most kits. Fortune Auto delivers hand-built construction with custom valving on every kit. Each one has a place in performance suspension, and the right one depends on your car and your roads.

Whatever you pick, the basics of ownership stay the same. Keep the threads clean, check that each locking collar is tight after you set ride height and look at the shaft seal at every service.

Frequently Asked Questions